Latch unit

ABSTRACT

Latch units are known components of loading systems for use in an aircraft cargo hold in which roller and ball units attached within or on a floor of a cargo hold operate in such a way that containers, pallets or similar items of freight can be conveyed into said hold through a door leading thereto and anchored at specified positions within the cargo hold. The present latch unit comprises a claw that can be depressed out of an elevated, operating position, in which an item of freight can be brought into an immobilizing engagement with the claw, into a resting position in which an item of freight can travel over the latch unit, this lowering movement being achieved by means of an actuator such as a ramp, lever or similar device when the latter are encountered by an approaching item of freight. The actuator is so constructed and the latch unit fixed in position in the region of the door in such a way, that when an item of freight approaches in a direction leading out of the cargo hold and through the door, the claw remains in the operating position, whereas when approached from all other directions the claw is depressed into the resting position. As a result, a considerable increase in the security of operation is achieved because, when a container rotates while in the door region, the latch unit cannot be damaged, and an unintended rolling of a container out of the cargo hold is prevented.

RELATED U.S. APPLICATIONS

[0001] Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.

REFERENCE TO MICROFICHE APPENDIX

[0003] Not applicable.

FIELD OF THE INVENTION

[0004] The invention relates to a latch unit comprising a component of a loading system for a cargo hold of an aircraft.

BACKGROUND OF THE INVENTION

[0005] When the cargo hold in an aircraft is being loaded with containers, pallets or similar items of freight, the containers are conveyed into the aircraft cargo hold through a door 12, as is shown in the attached FIG. 6. In the process, the containers 10 first enter the cargo hold by rolling along ball mats 14, being driven by power drive units 18 that operate in a direction perpendicular to the long axis of the aircraft, and are then conveyed to the final storage site on roller tracks that run in the long direction of the aircraft. They are retained there by latch units 24 that engage the container's lower edges 20. Such an arrangement is disclosed in the German patent 2 161 735; the latch units described in that document are initially lowered by hand into a retracted state before loading, so that the containers can roll over them, and only thereafter are manually brought into the locking position, when the containers are standing in the right place.

[0006] To prevent damage from being caused by latch units that have accidentally been left in the raised position, latch units have been designed such as are described, e.g., in German patent DE 195 44 796 C1; when a moving container encounters such a unit, the unit is pressed downward in a direction perpendicular to the locking position, i.e. perpendicular to the edge of the container that would otherwise be engaged by the unit.

[0007] The problem is especially critical in the region near the door to the cargo hold, because relatively long items of freight or certain kinds of containers are rotated while in this region and must then be transported further in a direction 900 away from the direction in which they entered. Because of this turning movement of the freight items, the latch units present in this region must be fixed mechanically in their retracted resting position.

[0008] Another problem is that during loading and unloading of the cargo hold in an aircraft, the floor of the hold may be tilted or unintended movements of the freight may be caused in other ways, with the result that the freight can roll out of the storage hold through the door and thus endanger the personnel working there.

BRIEF SUMMARY OF THE INVENTION

[0009] It is an object of the present invention to disclose a latch unit of the type mentioned above which provides greater safety and reliability during loading of an aircraft than those of the prior art.

[0010] According to the present invention there is provided a latch unit comprising a component of a loading system for a cargo hold of an aircraft in which roller and ball units are provided on a floor of a cargo hold in such a way that items of freight can be conveyed into said hold through a door leading thereto and can be anchored at specified positions within the cargo hold, the latch unit comprising a claw that can be depressed from an elevated, operating position, in which an item of freight can be brought into an immobilizing engagement with the claw, into a resting position, in which an item of freight can travel over the latch unit, and a mechanical actuator which causes the lowering movement when the actuator is encountered by an approaching item of freight, the actuator being so constructed and the latch unit being capable of location in position in the region of the door in such a way, that when an item of freight approaches the latch unit in a direction leading out of the cargo hold and through the door, the claw remains in the operating position, whereas when approached from all other directions it is depressed into the resting position.

[0011] A distinguishing feature of the latch unit is that the actuator is so constructed, and the unit can be fastened in the region of the door in such a way, that when a freight item approaching from the direction of the cargo hold is about to pass through the door, the claw remains in the operating position, whereas when freight approaches from any other direction the claw is retracted into the resting position. This makes it possible for such latch units to be disposed in the door region (i.e., not only at the very edge) of the cargo hold. That is, if the items of freight make a turning movement in this region, the latch units are retracted so that they cannot be damaged, but if the movement is directed towards the door, i.e. out of the cargo hold, the freight item is caught by the latch units and cannot accidentally emerge from the cargo hold.

[0012] Preferably, the claw defines an engagement surface and comprises a hinged joint disposed opposite to the engagement surface, which surface and joint are each so arranged that the engagement surface can be lowered against the force of a spring-loading in a movement substantially tangential to the hinge joint from the operating position into the resting position. This simple construction ensures a high degree of stability and hence of reliability in operation.

[0013] The shape of the claw is preferably such that it appears substantially rectangular in plan view, with surfaces that slant upward from the margin toward a middle region of an upper edge of the engagement surface. These inclined surfaces thus provide, by simple means, a mechanical device that causes the claw to be lowered, because a container that is approaching (from a direction other than the direction to be blocked) contacts the inclined surface with its edge and can slide along that surface, pressing the claw downward.

[0014] The latch unit comprises a locking mechanism to hold the claw in a position at least as deeply retracted as the resting position. Thus when the contents of the cargo hold are to be removed, the claw is folded down, so that while the containers are being conveyed out, the latch unit is in an inactive position.

[0015] The locking mechanism is preferably so constructed, and the latch unit can be attached to the floor of the cargo hold in such a way, that when the claw is pressed downward from the operating position sufficiently that it is lower than the resting position by a predetermined amount, it comes into engagement with the locking mechanism and is held therein until the locking mechanism is released. As a result, by a simple means it is ensured that the claw does not become fixed by the locking mechanism when such fixation is not desired, because an item of freight has accidentally struck it and caused it to be depressed into the resting position to avoid damage.

[0016] It is especially advantageous for the latch unit in accordance with the invention to be used in a loading system for an aircraft cargo hold in which containers, pallets or similar items of freight are conveyed through a door of the hold onto a floor within it. In this case the latch unit comprises a claw that can be actuated by ramps, levers or similar actuation devices in such a way that the claw, initially in an elevated operating position in which the freight items can come into locking engagement with the claw, can be lowered into a resting position in which an item of freight can travel over the latch unit. Here the actuator is so constructed, and the latch unit can be attached in the region of the door in such a way, that when the item of freight approaches from a direction out of the cargo hold and begins to go through the door, the claw remains in the operating position, whereas when approached from all other directions the claw is lowered into the resting position. Such a security mechanism obviously offers major advantages.

[0017] The present invention will now be described in greater detail by way of example with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0018]FIG. 1 is a perspective drawing of a latch unit in an elevated, operating position;

[0019]FIG. 2 is a perspective drawing of the latch unit shown in FIG. 1 in a retracted, resting position;

[0020]FIG. 3 is a side view of the latch unit shown in FIGS. 1 and 2 in its lowest, mechanically immobilized position;

[0021]FIG. 4 is a side view of the latch unit shown in FIGS. 1 and 2 in the lowest position in which objects can travel over it but in a position wherein it is not yet immobilized;

[0022]FIG. 5 is a side view of the latch unit shown in FIGS. 1 and 2 in its highest operating position; and

[0023]FIG. 6 shows in perspective a cargo hold of an aircraft such as is generally known.

DETAILED DESCRIPTION OF THE INVENTION

[0024] In the following description, the same reference numerals are used for identical parts or parts with identical actions.

[0025] A latch unit 22 comprises a claw 30 that is pivotably attached to a base 45 by way of a hinge 38, 38′ disposed at the outer edges. In each of the two hinge joints 38, 38′ a spring 39, 39′ is provided, which applies an upwardly directed stress tending to drive the claw 30 away from the base 45. By way of the base 45 the latch unit 22 can be fastened to the floor of the cargo hold, in fixation devices provided there, by means of fixation bolts 44.

[0026] The claw comprises an engagement surface 36 which, as can be seen in FIG. 5, is substantially perpendicular to the base 45 and hence also to the floor of the cargo hold, when the claw is in the raised operating position, as shown in FIGS. 2 and 5. In plan view, the claw 30 has a substantially rectangular contour; its surface is divided into several sections tilted upwards from the outer edges 40, 41 and 42, namely the sloped surface 31, which forms a ramp set at 90° with respect to the engagement surface 36, the sloped surface 32, which forms a ramp at 180° to the engagement surface 36, and the sloped surface 33, which forms a ramp at 270° to the engagement surface 36. Where there would otherwise be an edge between the adjoining sloped surfaces 31 and 32, as well as 32 and 33, these edges are chamfered sufficiently to form additional sloped surface 34, which is set at 135° to the engagement surface 36, and additional sloped surface 35, which is set at 315° to the engagement surface 36. All the sloped surfaces 31 to 35 come together substantially in the middle of the upper edge 37 of the engagement surface 36. This overall configuration, which is very simple to produce, ensures that the claw 30 is always pushed downward whenever it is encountered by an item of freight traveling in a direction other than perpendicularly towards the engagement surface 36. Therefore it can be used in the region of the door 12 of the cargo hold (see FIG. 6) as a means of reliably preventing an item of freight from accidentally proceeding out of the cargo hold.

[0027] In this situation, to enable containers to be unloaded, the latch unit is provided with a locking lever 43 comprising a catch mechanism that can engage a catch pin (not shown) on the claw 30 whenever the claw is pushed downward from its operating position (FIG. 5) beyond the retracted position (FIG. 4), until it reaches the depth shown in FIG. 3. In this lowest position the locking lever 43 snaps into an engaged state, retaining the claw 30 in this position so that the freight items can be unloaded from the cargo hold. 

1. A latch unit comprising a component of a loading system for a cargo hold of an aircraft in which roller and ball units are provided on a floor of a cargo hold in such a way that items of freight can be conveyed into said hold through a door leading thereto and can be anchored at specified positions within the cargo hold, the latch unit comprising a claw that can be depressed from an elevated, operating position, in which an item of freight can be brought into an immobilizing engagement with the claw, into a resting position, in which an item of freight can travel over the latch unit, and a mechanical actuator which causes the lowering movement when the actuator is encountered by an approaching item of freight, the actuator being so constructed and the latch unit being capable of location in position in the region of the door in such a way, that when an item of freight approaches the latch unit in a direction leading out of the cargo hold and through the door, the claw remains in the operating position, whereas when approached from all other directions it is depressed into the resting position.
 2. A latch unit as claimed in claim 1 wherein the claw defines an engagement surface and comprises a hinged joint disposed opposite to the engagement surface, which surface and joint are each so arranged that the engagement surface can be lowered against the force of a spring-loading in a movement substantially tangential to the hinge joint from the operating position into the resting position.
 3. A latch unit as claimed in claim 2, wherein an upper surface of the claw defines a substantially rectangular contour with sloping portions that incline upwardly toward a middle region of an upper edge of the engagement surface from outside edges of the claw.
 4. A latch unit as claimed in claim 1, comprising a locking mechanism for retaining the claw in a retracted position wherein it is at least as depressed as in its resting position.
 5. A latch unit as claimed in claim 4, wherein the locking mechanism is so constructed, and the latch unit can be attached to the floor of the cargo hold in such a way that the claw comes into engagement with the locking mechanism whenever the claw is depressed out of the operating position into a position lower by a predetermined amount than the resting position, and is thereafter retained by the locking mechanism until the locking mechanism is released.
 6. The use of a latch unit as claimed in claim 1 in a loading system for a cargo hold of an aircraft, in which items of freight can be conveyed through a door of the cargo hold onto a floor of said hold, wherein the latch unit comprises a claw that can be depressed from an elevated, operating position, in which an item of freight can be brought into an immobilizing engagement with the claw, into a resting position, in which an item of freight can travel over the latch unit, and a mechanical actuator which causes the lowering movement when the actuator is encountered by an approaching item of freight, the actuator being so constructed and the latch unit being located in position in the region of the door in such a way, that when an item of freight approaches the latch unit in a direction leading out of the cargo hold and through the door, the claw remains in as the operating position, whereas when approached from all other directions it is depressed into the resting position. 